1. Field of the Invention
The present invention relates to an image synthesizing apparatus that synthesizes a plurality of images to obtain a moving image, a control method therefor, and a computer-readable storage medium storing a control program for implementing the method.
2. Description of the Related Art
In recent years, various methods have been proposed for image stabilization in image pickup apparatuses such as digital cameras. Among them, there are methods in which shooting is performed to take a plurality of underexposed images at a shutter speed at which camera shake is not likely to occur, and after the shooting, the plurality of images are synthesized to obtain a correctly-exposed image.
For example, there is a method in which when images are to be synthesized, images are subjected to temporal alignment (also called displacement correction) and then synthesized to generate one still image (see Japanese Laid-Open Patent Publication (Kokai) No. H05-7336).
Further, there is a method in which not all of images obtained as a result of shooting are synthesized, but the number of images required for synthesis is determined according to image information obtained during shooting, and the determined number of images are synthesized (see Japanese Laid-Open Patent Publication (Kokai) No. 2006-191305 or Japanese Laid-Open Patent Publication (Kokai) No. 2006-253810).
According to any of the patent literatures mentioned above, still images are synthesized, and if moving images are to be synthesized, not only processing time required for synthesis would increase but also the amount of data transferred to memory would increase.